Site factors and the climatologcal elements observed during the 1962 field season in central Axel Heiberg Island, N. W. T., Canada, are discussed and comjparisons made between ice-covered and bare-ground enviornments. Heat-balance computations for the Lower Ice Station, White Glacier, for the period 16 - 31 July, when 65 cm. of ice ablated, indicate that net radiation was responsible for 66 per cent of the total heat supplied to the glacier's surface, sensible heat 28 per cent and latent heat, in the form of condensation, 6 per cent. Of the total amount of heat available at the ice surface about 88 per cent was consumed in the melt-process and 12 per cent used to heat the underlying cold ice.

Different methods of calculating heat balance for short periods of one or two days are critically examined, particularly some of the assumptions underlying the calculations of sensible and latent heat quantities. Preference is given to a technique which assumes a logarithmic law for the wind speed, temperature and vapour-pressure profiles and which avoids using the measured ablation for the computation of turbulent fluxes. It is demonstrated that short-term ablation calculated from surface-lowering observations is frequently not representative of true melt. The conclusion reached is that with the present accuracy of measurements and techniques of evaluation, heat-balance calculations for periods of only one or two days' duration are not reliable enough to warrant the great effort involved. (from the Abstract)